Fixed clipping plane in painter gizmos:

Obsolete variable m_clipping_plane was used instead of getting the clipping plane from
the common gizmo data pool. This means the clipped parts of objects captured hits and
could not be painted through.
The clipped_mesh_was_hit variable is obsolete now. It was a mistake to introduce it in the first place.

src/slic3r/GUI/Gizmos/GLGizmoPainterBase.hpp

@@ -101,8 +101,6 @@ private:
                               const Camera& camera,
                               const std::vector<Transform3d>& trafo_matrices) const;
 
-    float m_clipping_plane_distance = 0.f;
-    std::unique_ptr<ClippingPlane> m_clipping_plane;
     GLIndexedVertexArray m_vbo_sphere;
 
     bool m_internal_stack_active = false;
@@ -126,7 +124,6 @@ private:
         int mesh_id;
         Vec3f hit;
         size_t facet;
-        bool clipped_mesh_was_hit;
     };
     mutable RaycastResult m_rr;